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lockdown: Lock down perf when in confidentiality mode

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Disallow the use of certain perf facilities that might allow userspace to
access kernel data.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
David Howells 2019-08-19 17:18:00 -07:00 committed by James Morris
parent 9d1f8be5cf
commit b0c8fdc7fd
3 changed files with 9 additions and 0 deletions
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1
include/linux/security.h
View File

@ -119,6 +119,7 @@ enum lockdown_reason {
LOCKDOWN_KCORE, LOCKDOWN_KCORE,
LOCKDOWN_KPROBES, LOCKDOWN_KPROBES,
LOCKDOWN_BPF_READ, LOCKDOWN_BPF_READ,
LOCKDOWN_PERF,
LOCKDOWN_CONFIDENTIALITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX,
}; };

7
kernel/events/core.c
View File

@ -10798,6 +10798,13 @@ SYSCALL_DEFINE5(perf_event_open,
perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
return -EACCES; return -EACCES;
err = security_locked_down(LOCKDOWN_PERF);
if (err && (attr.sample_type & PERF_SAMPLE_REGS_INTR))
/* REGS_INTR can leak data, lockdown must prevent this */
return err;
err = 0;
/* /*
* In cgroup mode, the pid argument is used to pass the fd * In cgroup mode, the pid argument is used to pass the fd
* opened to the cgroup directory in cgroupfs. The cpu argument * opened to the cgroup directory in cgroupfs. The cpu argument

1
security/lockdown/lockdown.c
View File

@ -34,6 +34,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_KCORE] = "/proc/kcore access", [LOCKDOWN_KCORE] = "/proc/kcore access",
[LOCKDOWN_KPROBES] = "use of kprobes", [LOCKDOWN_KPROBES] = "use of kprobes",
[LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM", [LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM",
[LOCKDOWN_PERF] = "unsafe use of perf",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
}; };